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The Science of Nature

, 102:69 | Cite as

Physiological implications of the abnormal absence of the parietal foramen in a late Permian cynodont (Therapsida)

  • Julien BenoitEmail author
  • Fernando Abdala
  • Marc J. Van den Brandt
  • Paul R. Manger
  • Bruce S. Rubidge
Short Communication

Abstract

The third eye (pineal eye), an organ responsible for regulating exposure to sunlight in extant ectotherms, is located in an opening on the dorsal surface of the skull, the parietal foramen. The parietal foramen is absent in extant mammals but often observed in basal therapsids, the stem-group to true mammals. Here, we report the absence of the parietal foramen in a specimen of Cynosaurus suppostus, a Late Permian cynodont from South Africa (SA). Comparison with Procynosuchus delaharpeae, a contemporaneous non-mammalian cynodont from SA, demonstrates that the absence of this foramen is an abnormal condition for such a basal species. Because seasonality was marked during the Late Permian in SA, it is proposed that the third eye was functionally redundant in Cynosaurus, possibly due to the acquisition of better thermoregulation or the evolution of specialized cells in the lateral eyes to compensate for the role of the third eye.

Keywords

Cynodontia Therapsida Parietal foramen Pineal Thermoregulation Paleoneurology 

Notes

Acknowledgments

The authors thank Dr. Jashashvili (ESI) for CT scanning and Z. Erasmus for granting the access to the Iziko Museum collections. This research was conducted with the financial support from the DST/NRF Centre of Excellence in Paleosciences, the NRF African Origins Platform, and PAST (the Paleontological Scientific Trust) and its Scatterlings projects.

Compliance with Ethical Standards

Conflict of interest

The authors declare no conflict of interest.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Julien Benoit
    • 1
    • 2
    Email author
  • Fernando Abdala
    • 1
  • Marc J. Van den Brandt
    • 1
  • Paul R. Manger
    • 2
  • Bruce S. Rubidge
    • 1
    • 3
  1. 1.Evolutionary Studies Institute (ESI), School of GeosciencesUniversity of the WitwatersrandJohannesburgSouth Africa
  2. 2.School of Anatomical SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
  3. 3.School for GeosciencesUniversity of the WitwatersrandJohannesburgSouth Africa

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